<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
 <c:set var="age" value="20"></c:set>
   ${age}
   <hr/>
   <!-- 但条件判断 -->
   <c:if test="${age == 20}">
     今年20岁了
   </c:if>
   <hr/>
</body>
</html>